Add Salt 2018.3 tests

Change-Id: If07ba2a0b7e9b4a29a97161db423d236de0b3844
diff --git a/.kitchen.yml b/.kitchen.yml
index cfb7f2a..b657514 100644
--- a/.kitchen.yml
+++ b/.kitchen.yml
@@ -35,7 +35,7 @@
 platforms:
   - name: <%=ENV['PLATFORM'] ||  'saltstack-ubuntu-xenial-salt-stable' %>
     driver_config:
-      image: <%=ENV['PLATFORM'] || 'epcim/salt-formulas:saltstack-ubuntu-xenial-salt-stable'%>
+      image: <%=ENV['PLATFORM'] || 'epcim/salt:saltstack-ubuntu-xenial-salt-stable'%>
       platform: ubuntu
 
 suites: